Hovering apparatus for submarines and other buoyant objects



May 26, 1959 c. R. HANNA ET Al.

HOVERING APPARATUS FOR SUBMARINES AND OTHER BUOYANT OBJECTS Filed 001'.. 13. 1953 4 Sheets-Sheet 1 IIII'IIIIIIIILIIIIIIIIIIIIIN I I l I l I l I I I l I I I l l I I I I l l l I I I I I I I I l I I I Il May 26, 1959 c. R. HANNA ET AL 2,887,976

HOVERING APPARATUS FOR SUBMARINES AND OTHER BUOYANT OBJECTS Filed Oct. 13', 1953 4 Sheets-Sheet 2 INVENTORS CLINTON R. HANNA WYILLIAM O. OSBON BMW Wa/m ATTORNEYS ATTO May 26, 1959 c.-R;HANNA ETAL i HOVERTNG APPARATUS FOR suBMARTNRs ANO OTHER BUOTANT OBJECTS Filed Ocnyls. 195:5

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May 26, 1959 c. R. HANNA ET AL 2,887,976

HOVERING APPARATUS FOR SUBMARINES- AND OTHER BUOYANT OBJECTS Filed 00T.. 15, 1953 4 SheebS-Shl; 4

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INVENTORS CLINTON R. HANNA WILLIAM O. OBON TT EY United States Patent O HOVERING APPARATUS FOR SUBMARINES AND OTHER lBUOYANT OBJECTS Clinton R. Hanna and William O. Osbon, Pittsburgh, Pa., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Application October 13, 1953, Serial No. 385,903

4 Claims. (Cl. 114-16) This invention relates to hovering apparatus and more particularly to an automatic apparatus for maintaining a oating submarine device at a substantially constant predetermined depth.

In the past, submarine boats hovered by an on-ol type of control in which ballast changes were elected discon- L tinuously by either blowing one tank containing sea water with compressedair when heavy, or by ooding another tank with sea water when light. This method was inaccurate and -required considerable supervision. Furthermore, this type of hovering control could be used for a limited time only, since the air supply for blowing was limited.

It is an object of this invention to provide an improved hovering apparatus for oating submarine objects.

It is another object of ythis invention to provide hovering apparatus for floating submarine devices, which apparatus utilizes a pump under the continuous control of a pressure sensing unit.

A further object of this invention is to provide automatic hovering apparatus for sumbarine boats, oating mines and the like, which apparatus permits accurate control of depth with little-hunting and a minimum of noise.

Other objects and advantages of the invention will hereinafter become more fully apparent from the following description of the annexed drawings, which illustrate a preferred embodiment, and wherein:

Fig. 1 is a block and line drawing showing the relationship of the apparatus of this invention:

Fig. 2 is a sectional view of the depth error unit shown diagramatically in Fig. 1; d

Fig. 3 is a circuit diagram of the electrical apparatus and the control circuit of the hovering device of Fig. 1; and f Fig. 4' is a sectional viewfof the regulating valve assembly of Fig. 1.

Referring now to the drawings and more particularly to Fig. 1, the referencev numeral designates the outer shell of a oating submarine object such as a submarine boat or lloating mine (hereinafter referred to as submarine), the object being indicated by interrupted lines. A pressure sensing unit 11, which produces an electrical signal 4in proportion to a deviation in pressure from a predetermined datum pressure, is mounted Within the shell 10.

The pressure sensing unit 11 is described and claimed in the co-pendin-g application Serial No. 387,336, of Charles G. Beatty and William O. Osbon, entitled Pressure Sensitive Device, filed October 20, 1953, now U.S. Patent 2,761,318, which is assigned to the assignee of this invention. AAfhousirrg 12, open to the sea, is divided by a iiexible rubber diaphragm 13 into a chamber 17 and a chamber 18. Sea pressure is transmitted through the diaphragm 13 and is transferred to the pressure sensing unit 11 through a tube 14 and through a tube and a valve 16.

The electrical output from the pressure sensing unit 11 vis coupled to an electronic ampliiierrS-and then to "ice a magnetic power amplifier 52. Field windings (one only being shown for simplicity) of a'direct current generator 137 are coupled to the output of the magnetic amplifier 52 so that the output of the generator 137 is controlled by the output of the magnetic amplifier 52. The generator 137 is driven by an electric motor which is energized from any convenient source (not shown) in the submarine 10. Thedirect current output of the generator 137 energizesa direct current motor 151 which drives a reversible ow pump 152.

A ballast or hovering tank 153, which may be filledI with sea Water to increase the weight and which may be emptied to decrease the weight of the submarine 10, is mounted thereon. A conduit 154 connects the hovering tank 153 with the pump 152 and a second conduit 155 connects the pump 152 with the sea, enabling the pump 152 to pump sea water directly either into or out from the hovering tank 153. The hovering tank 153 is closed with respect to the interior of the submarine 10 because the tank 153 is at a higher lpressure than the interior of the submarine 10 when the latter submerges deeply. The hovering tank 153 contains some air, and when sea water is pumped into the hovering tank 153, the air contained therein is compressed. Since the volume of the submarine 10 is substantially constant, the specific gravity of the submarine 10 as a whole is varied with variations in the weight of the sea water contained in the hovering tank 153.

The pressure difference between the hovering tank 153 and the sea should be kept small to reduce the power required by the pump 152. This is accomplished by regulating the pressure of the air contained within the hovering tank 153 so that it does not diier from the sea pressure by more than a prescribed amount. A regulating valve assembly 156 is provided for this purpose. The pressures between zero and the prescribed maximum pressure difference between the sea and the air in the hovering tank 153 is called the dead band of the valve assembly 156. Water may be pumped into and out from the hovering tank 153 repeatedly without the expenditure of air providedthat during the pumping operation, the pressure dilference 'between the sea and the tank 153 remains within the dead band. A tube 157 connects the valve assembly 156 with the sea and a tube 158 connects a supply of compressed air (not shown) to the valve assembly 156. Ai-r is fed from the valve assembly 156 through a tube 159 to the hovering tank 153 and is exhausted from the system by a tube 161.

GENERAL OPERATION The va1ve`16 is closed when the submarine Ais at the depth at which it is to hover, thereby establishing a reference pressure in the pressure sensing unit 11. A change in the depth of the submarine 10 produces an electrical signal in the output of the pressure sensing unit 11 in a manner to be described in more detail hereinafter. The ouput signal of the pressure sensing unit 11 is amplified by the :electronic and lmagnetic amplifiers 50 and 52 and the magnetic amplifier 52 energizes the field windings 135 of the direct current generator 137 to control its output. The motor 151 operates in response to the output of the .generator 137 and drives the pump 152 to pump water into or ont of the hovering tank 153. When the submarine 10 drops to a depth greater than the hovering depth, the signal output of the pressure sensing unit 11 is such that the pump 152 pumps water out of the hovering tank 153` to lighten the submarine 10 and cause it to rise. vIfthe submarine 10 rises above the hovering depth, the output signal from -the pressure sensing unit Iltis suchy 3 that the pump 152 pumps water into the hovering tank 153.

For a better understanding of the structure and operation of the hovering device of this invention, reference is now made to Figs. 2, 3 and 4 of the drawings and to the following detailed description of the elements of the apparatus.

PRESSURE SENSING UNIT 11 Description f pressure sensing zmz't l] Referring now to Fig. 2, the reference numeral 21 designates an upper cylindrical container which is positioned on a lower cylindrical container 31. A cylindrical bellows 22 in the container 21 is secured to a lower wall thereof and communicates through an opening 20 with the lower container 31. A rigid circular plate 23 is secured to the upper wall of the bellows 22. A horizontal partition 33 is secured approximately midway in the lower container 31 and has a center opening 40. A plurality of evacuated cylindrical bellows 32A have their bottom ends secured to the partition 33 and their upper ends to a circular plate 34. A cylindrical central bellows 35 is secured at its upper end to the upper plate 34 and is secured at its lower end to the partition 33 to surround the opening 40. The partition 33 and the central bellows 35 divide the lower container 31 into an upper cavity 36 and a lower cavity 37. A rod 38 extends through the central bellows 35 and the opening 40 from the upper plate 34 to a lower plate 39. A plurality of springs 41 are positioned between the lower plate 39 and the bottom wall of the container 31 to bias the upper and the lower plates 34 and 39 upwardly. The evacuated bellows 32A bias the upper and the lower plates 34 and 39 downwardly.

The Sea is admitted to the chamber 17 of the housing 12, and the chamber 18 connects, through the tube 14, with the upper container 21 at a point above the bellows 22. The tube connects the tube 14 with the lower container 31.

The upper container 21, the upper cavity 36 and the tubes 14 and 15 are lled with a noncorrosive and electrically `insulating fluid. The lower cavity 37 is filled with air.

A double-acting safety valve 19 is provided as a safeguard against excessive differences in pressure between the portion of the upper container 21 external to the bellows 22 and the cavity 36. The safety valve 19 comprises a housing 48 in which two valve seats 46 and 47, which face in opposite directions and against which two valve disks 42 and 43 are biased by valve springs 44 and 45 respectively, are mounted. The valve disks 42 and 43 are normally seated, but excessive pressure diierences will cause one or the other of them to unseat to relieve the pressure. The purpose of the safety valve 19 is to limit the strain on the bellows 22 and on certain resistors which will be described subsequently.

Operation of pressure sensing unit 1] In operation, the valve 16 is opened and the sea is introduced into the chamber 17 of the housing 12, causing the diaphragm 13 to Hex. The flexing of the diaphragm 13 places the uid in the tubes 14 and 15 and in the containers 21 and 31 under compression, and the bellows 32A and 35 and the springs 41 are compressed. After the bellows 32A and 35 have come to rest, and the submarine 1() is at the depth at which it is to hover, the valve 16 is closed, sealing the fluid in the cavity 36 and maintaining it under the pressure of the sea which existed when the valve 16 was closed.

As long as the pressures of the uids on both sides of the bellows 22 in the upper container 21 are the same, the plate 23 remains in the intermediate position shown in Fig. 2, but when the sea pressure increases, a pressure differential is created across the bellows 22, and the bellows 22 is compressed until the pressures are again equalized. When the bellows 22 is compressed, the plate 23 is moved downwardly. On the other hand, when the pressure of the sea decreases, the bellows 22 and the plate 23 respond by moving in the opposite direction. The displacement of the plate 23 from its intermediate position is `substantially proportional to the diierence in the pressure of the sea and the pressure of the iiuid in the cavity 36, and the direction of its displacement denotes which of the two pressures is the greater.

To produce an electrical signal by the displacement of the plate 23, tension sensitive resistors 24 and 25, often referred to as strain gages, are secured to extend between the plate 23 and an upper wall of the container 21, and tension sensitive resistors 2S and 29 are secured to extend between the plate 23 and a lower wall of the container 21. The resistors 24, 25, 28 and 29 are prestressed by tensioning devices 26, 27, 51 and 32 respectively, and are connected by wires (not shown) to a terminal housing 30 which is mounted on a side wall of the container 21.

ELECTRONIC AMPLIFIER 50 Description of electronic amplifier 50 rlhe resistors 24, 25, 28 and 29 are connected in the form of a Wheatstone bridge 61 (see Fig. 3), with one end of the resistor 24 connected to one end of the resistor 29, the other end of the resistor 29 connected to one end of the resistor 25, the other end of the resistor 25 connected to one end of the resistor 28, and the other end of the resistor 28 connected to the other end of the resistor 24. Energy is supplied to the bridge 61 from a power supply 62 through leads 63 and 64 which are connected to the junctions of the resistors 25--28 and 24-29 respectively, and the output of the bridge 61 is taken from the junction of the resistors 28 and 24, and the junction of the resistors 29 and 25. A potentiometer 65, connected across the leads 63 and 64 with its slide connected to one Side of the bridge output, is provided to balance the bridge 61 when the pressure difference in the pressure sensing unit 11 is Zero. A high value variable resistor 66, connected to the other side of the bridge output, is in series with .the slide of a low value potentiometer 67 which is connected between the leads 63 and 64. The variable resistor 66 and the potentiometer 67 are provided for coarse or ne adjustment of the output of the bridge 61 at pressure diiferences other than zero.

The output of the bridge 61 is coupled through an impendance matching transformer 68 to the iirst stage 69 of the electronic amplifier 50. The output of the rst amplifier stage 69 is connected to a second stage 71, and the output of the stage 71 is applied to two parallel connected stages 72 and 73. The amplier stages 69, 71, 72 and 73 are normal resistance-capacitance coupled amplifiers. The energy supplied to the bridge 61 by the power supply 62 is alternating, and the amplied alternating signal from the parallel stages 72 and 73 is coupled through a transformer 74 comprising a primary 74A and two secondaries 74B and 74C to a converter 75 for frequency and phase conversion. The converter 75 comprises four vacuum tube diodes 76, 77, 78 and 79. The diodes 76 and 77 have their anodes connected together through the secondary 74B and their cathodes connected together through two serially connected resistors 81 and 82. The diodes 78 and 79 have their anodes connected together through the secondary 74C and their cathodes connected together through the resistors 81 and 82. The cathodes of the diodes 77 and 78 are connected to one side of the resistor 81 and the cathodes of the diodes 76 and 79 are connected to one side of the resistor 82. The other sides of the resistors 81 andv82 are connected together.

A reference alternating voltage from the same source that supplies the power supply 62 is applied to the con* verter 75 through a transformer 83 comprising a primary 83A and a center-tapped secondary having two portions 83B and 83C. A lead 84A connects the center of the secondary 74C with one side of the portion 83B, a lead 84B connects the center of the secondary 74B with one side of the portion 83C, and a lead 84C connects the junction of the resistors 81 and 82 with the center tap between the portions 83B and 83C. The outputs from the converter 75 are the voltages appearing across the resistors 81 and 82.

A meter 86 is connected across the output from the converter 75 and produces a visual indication of the output from the bridge 61. The output from the converter 75 is connected into a differentiating and summation network comprising a resistor 87 connected in series with the meter 86, a resistor 88 connected in parallel with the meter 86 and the resistor 87, and a capacitor S9 connected between the resistor 87 and the resistor 88 and in series with the output of the converter 75. The original converter signal is created across a resistor 91, which resistor is connected in series with the meter 86 and the resistor 87 to complete the path across the output from the converter 75, and the derivative signal is added to the converter signal across the resistor 88 which is also in series with the resistor 91.

The original converter signal and its first derivative are then applied to a first push-pull connected direct-coupled amplifier stage comprising tubes 92 and 93, the signal across the resistor y81 being applied to the tube 92 and the signal across the resistor 82 being applied to the tube 93. In the output of the tubes 92 and 93, a second differentiating and summation network is connected, said network comprising resistors 95, 100 and 97 connected in series across the output of the two tubes 92 and 93; capacitors 101 and 102 connected in series with the output of the tubes 92 and 93 respectively; a resistor 96 connected across the capacitor 101 to the junction of the resistors 95 and 100; and a resistor 98 connected across the capacitor 102 to the junction of the resistors 97 and 100. The original signal and its first derivative both appear across the resistor 100 and the second derivative is added to the other components by the resistors 96 and 98. The composite signal comprising the original converted signal, its first derivative and its second derivative is applied to a final push-pull connected direct-coupled amplifier stage comprising tubes 103 and 104, the signal from the tube 92 being applied to the tube 103 and the signal from the tube 93 being applied to the tube 104. The output of the first push-pull connected stage is balanced by a potentiometer 94 which is connected between the anodes of the tubes 92 and 93 and has its slide connected to a high voltage positive lead 90 from the power supply 62. Capacitors 105 and 106 are connected across the output of the final push-pull stage to remove any ripple present in the converted signal, and the composite signal is then applied to the magnetic power amplifier 52 by leads 110. Energy is supplied the tubes 103 and 104 by the high voltage lead 90 which is connected to the junction of the capacitors 105 and 106.

Operation of electronic amplifier 50 The resistor bridge 61 is balanced when the valve 16 is open by adjusting the potentiometer 65 until the meter 86 indicates zero output from the bridge 61. A difference in pressure across the bellows 22 of the pressure sensing unit 11 unbalances the bridge `61 by changing the stresses and thereby the resistances of the resistors 24, 25, 28 and 29. When the bridge 61 is unbalanced, an output signal is created which Varies in amplitude and phase in dependence upon the degree and direction of the bridge unbalance. The output signal from the bridge 61 is amplified bythe amplifiers 69, 71, 72 and 73 and is then applied to the primary 74A of the transformer 74. Two voltages of the same phase are induced in the two secondaries 74B and 74C of the transformer 74, and are then applied to the diodes 76, 77, 78 and 79 of the converter 75'. Since the diodes 76, 77, 78 and 79 are unidirectional conductors, current at any instant ows through only two of them, the other two being of a polarity to conduct in the opposite direction. The voltage induced in the secondary of the transformer 83 also is applied to the converter 75 and the two voltages combine in the following manner to produce two resultant direct voltage signals in the output from the converter 75.

Assume that current ows in the primary 83A in such a direction that the voltage induced in the secondary is positive on the left and negative on the right. The lead 84A is positive with respect to the lead 84C, and the lead 84C is positive with respect to the lead 84B. Assume also that the current flow through the primary 74A of the transformer 74 is such that the top of both of the secondaries 74B and 74C are positive and the bottoms of the secondaries are negative. Current would tend to iiow through the diode 78, through the lead 84C and through the portion 83B of the transformer 83 from right to left. However, the voltage of the portion 83B has been defined as opposing this flow of current, and the current fiow from the secondary 74C through the portion 83B is accordingly small. At the same time, the voltage induced in the secondary 74B causes current to flow through the diode 76, the resistor 82, the lead 84C and through the portion 83C from left to right to the lead 84B. In this case, the current flow from the secondary 74B and the voltage induced in the portion 83C are aiding, and the current flow through the resistor 82 is accordingly large. The current fiowing through the diode 78 traverses the resistor 81 and produces a voltage drop across it, and the current flowing through the diode 76 traverses the resistor 82 producing a voltage drop across it.

Thus, when the bridge 61 is balanced, the voltage drop-s across the resistors 81 and 82 are equal but in opposite directions. When the bridge 61 becomes unbalanced, the voltage across one of the resistors 81 or 82 increases and the voltage across the other resistor decreases, the increase and decrease depending upon the degree of unbalance of the bridge 61. Whether the voltage across a particular resistor 81 or 82 increases or decreases depends upon the phase relationship between the output of the bridge 61 and the output of the tranformer 83. For the converter 75 to function properly, the voltage applied to the transformer 83 must be of exactly the same frequency and must bearan unchanging phase relationship with the Voltage applied to the input to the bridge 61. If the output of the bridge 61 were reversed in phase, the diodes 77 and 79 would conduct, and the resistor 81 would be tra-versed by a large current tiow while the resistor 82 would be traversed by a small current flow.

The output voltages of the converter 75 are taken across the resistors 81 and 82 and applied to the first differentiation circuit. Differentiation is desirable to increase the speed of response of the generator 137 and to overcome the mechanical and electrical inertia of the system. The composite signals are amplified by the direct-coupled amplifier tubes 92 and 93; the tube 92 receiving the voltage appearing across the resistor S1 and the tube 93 receiving the voltage appearing across the resistor 82, and are again differentiated by the second differentiation circuit. The final direct-coupled amplifier tubes 103 and 104 amplify the signals and introduce them into the magnetic amplifier 52. The tube 103 receives the amplified and differentiated voltage of the signal appearing across the resistor 81, and the tube 104 receives the amplied and differentiated voltage of the signal appearing across the resistor 82.

MAGNETIC AMPLIFIER 52 Description of magnetic amplifier 52 The magnetic amplifier 52 comprises four saturable core magnetic reactors 107, 108, 109 and 111. The

reactor 107 comprises an impedance winding 112, a control winding 131 and a bias winding 121. The reactor S comprises an impedance winding 113, a control winding 132 and a bias winding 122. The reactor 109 comprises an impedance winding 114, a control winding 133 and a bias winding 123. The reactor 111 comprises an impedance winding 115, a control winding 134 and a bias winding 124. The bias windings 121, 122, 123 and 124 are connected in series and are supplied with direct current from a full wave rectifier 127 through a variable resistor 128. The impedance winding 112 is connected at one end to one end of the impedance winding 113. A rectifier 141 is connected at one end to the other end of the impedance winding 112, and a rectifier 142, of opposite polarity to the rectifier 141, is connected at one end to the other end of the impedance winding 113. The other ends of the rectificrs 141 and 142 are connected together and to a power lead 117 which is connected to one side of a source of alternating current (not shown). A power lead 116 connects the other side of the source of alternating current with one input terminal of a full wave rectifier bridge 118. The other input terminal of the rectifier bridge 113 is connected to the junction of the impedance windings 112 and 113. The field winding 135 of the direct current generator 137 is connected across the output of the rectifier bridge 118.

The impedance winding 114 is connected at one end to one end of the impedance winding 115. A rectifier 143 is connected at one end to the other end of the impedance winding 114, and a rectiiier 144, of opposite polarity to the rectifier 143, is connected at one end to the other end of the impedance winding 115. The other ends of the rectifiers 143 and 144 are connected together and to the lead 117. The lead 116 is connected to one input terminal of a rectifier bridge 119 and the other input terminal of the rectifier bridge 119 is connected to the junction of the impedance windings 114 and 115. A held winding 136 of the direct current generator 137 is connected across the output of the rectifier 119 in such a manner that the current flow through it is in a direction opposite to the current iiow through the field winding 135. When the current flows through the field windings 135 and 136 are equal, their magnetic iiuxes cancel each other and the generator 137 generates no current. Capacitors 138 and 139 are connected across the field windings 135 and 136 respectively to bypass any alternating components in the field winding currents around the field windings 135 and 136.

The control windings 131 and 132 are connected in series, with one end of the control Winding 131 connected to the output of the tube 104 of the electronic amplifier 50, the other end of the control winding 131 connected to one end of the control winding 132 and the other end of the control winding 132 connected to the junction of the capacitors 105 and 106. The control windings 133 and 134 are connected in series, with one end ofthe control winding 133 connected to the junction of the capacitors 105 and 106, the other end of the control winding 133 connected to one end of the control winding 134 and the other end of the control winding 134, connected to the output of the tube 103 of the electronic amplifier 50. The control windings 131-132 and 133-134 are in series with the direct current supply to the tubes 104 and 103 respectively. The current fiow through the tubes 103 and 104 is in the same direction; from the junction of the capacitors 105 and 106, through the control windings, to the tubes 103 and 104; and the control windings 131, 132, 133 and 134 are connected so that the current iiow through them is in the same direction as the current fiow through their respective impedance windings, 112, 113, 114 and 115.

Operation of magnetic amplier 52 The reactors 107 and 108 form one channel which is controlled by the `signal output of the tube 103 of the iid electronic amplifier 50 and which in turn controls the current flow through the field winding 135 of the generator 137. The reactors 109 and 111 form a second channel which is controlled by the output from the tube 104, and which in turn controls the current iiow through the field winding 136. The current iiow through the bias windings 121, 122, 123 and 124 establishes equal magnetic iux through all of the reactor cores. The current lflow through the control windings 131, 132, 133 and 134 also creates magnetic iiux in the reactor cores and the amount of the flux created by control windings determines the total linx and the impedan-ce of each of the cores. When the bridge 61 is balanced, the outputs of the tubes 103 and 104 are equal, and the current flows through the control windings 131, 132, 133 and 134 are equal. The impedances of the reactor cores are also then equal, and the current iiowing through the impedance windings 112, 113, 114 and 115, and therefore through the field windings 135 and 136, are equal. As long as the currents fiowing through the field windings 135 and 136 are equal, the fluxes created therein cancel one another so that no current is generated by the generator 137.

When the bridge 61 is unbalanced, the current outputs from the tubes 103 and 104 change, the output of one of the tubes 103 or 104 becoming greater than the output from the other tube, and the currents through the control windings 131-132 and 133-134 also change. The change in the currents flowing through the control windings 131-132, and 133-134 change the impedances of the reactors 107-103 and 109-111 correspondingly, and the impedance in the circuits of the two field windings 135 and 136 are no longer the same. The different impedances in the circuits of the two ield windings 135 and 136 result in ditierent current iiows therethrough, and their iiuxes no longer completely cancel, producing an output from the generator 137.

The combinations of the rectifiers 141-142 and the impedance windings 112-113; and the rectiiiers 143-144 and the impedance windings 114-115, form networks through which direct currents circulate. The circulatory currents in these networks establish flux in the reactor cores 107, 108, 109 and 111 which produce regeneration, increasing the eiiect of a change in the control winding currents upon the impedance winding currents. The amount of regeneration can be controlled by connecting resistors 145 and 146 across the impedance windings 112-113 and 114-115 respectively; the higher the value of the resistors 145 and 146, the greater the regeneration.

REGULATING VALVE ASSEMBLY 156 Description of regulating valve assembly 156 Referring now to Fig. 4 which shows the regulating valve assembly 156 in section, the assembly 156 comprises two major components; a pressure regulating valve 162 and differential spring valves 163.

The pressure regulation valve 162 comprises a housing 171 having a central bore in which two valve seats 172 and 173 coaxial with the bore and facing in opposite directions are mounted. A valve disk 174 abuts the valve seat 172, and a valve disk 175 abuts the valve seat 173. Both valve disks 174 and 175 are slidable within the central bore of the housing 171. A valve spring 176 biases the valve disk 174 against the valve seat 172, and a valve spring 177 biases the valve disk 175 against the valve seat 173. A rod 178 passes through central openings in the valve disk 174 and the valve seats 172 and 173, and carries an actuating shoulder 179 with which to move the valve disk 174 from its seat 172. The lower end of the rod 178 abuts the Valve disk 175 to force the valve disk 175 from its seat 173 to open the valve, and the upper end of the rod 178 is aixed to a rubber diaphragm 181 at approximately the middle thereof.

The diaphragm 181 has a metal washer 180 for reinforcement adjacent each face and surrounding the upper end of the rod 178. The diaphragm 181 serves as a partition, being attached to the inside of the housing 171, and divides the housing 171 into cavities 182 and 183. The upper valve disk 174 separates the cavity 183 from a cavity 184 surrounding the seat 172, and the lower valve seat 173 and disk 175 separate the cavity 183 from a cavity 186. The tube 157 connects the cavity 182 with the sea, and the tube 158 connects the cavity 186 with a compressed air supply (not shown). The tube 161 is connected into the cavity 184, and a conduit 187 connects the cavity 183 with the differential spring valves 163.

The diiferential spring valves 163 actually comprise two spring valves; a positive differential valve 191 and a negative differential valve 192, having a single housing 171 in common with the regulation valve 162. The positive spring valve 191 has a valve seat 193 against which a valve disk 194 is pressed by a spring 195 mounted within the housing 171. The negative differential valve 192 comprises a valve seat 196 against which is pressed a valve disk 197 by a spring 198, al1 mounted within the housing 171. The conduit 187 from the regulation valve 162 is connected into the bottom of the positive valve 191 and into the top of the negative differential valve 192. The tube 159 connects the hovering tank 153 with the top portion of the positive diiferential valve 191 and the bottom portion of the negative dilferential valve 192.

Operation of regulating valve assembly 156 When the `sea pressure increases over the pressure of the air in the cavity 183 of the regulation valve 162, the diaphragm 181 is deflected downward, forcing the rod 178 and the valve disk 175 downward against the action of rthespring 177 and opening the valve. Compressed air is admitted into the cavity 183 through the open lower` valve and the tube 158, increasing the pressure of the air in the cavity 183. The increased air pressure in the cavity 183 drives air through the conduit 187 to the bottom of the positive differential spring valve 191, forcing back the valve disk 194 and opening the valve. The expanding air is then forced through the conduit 159 to the hovering tank 153. At the same time, the air from the compressed air supply, entering the cavity 183, forces the diaphragm 181 back into an intermediate position against the action of the sea pressure, thus withdrawing the rod 17 8 from the valve disk 175, allowing the spring 177 to again seat the valve disk 175 and cutting oi the supply of compressed air. If, after the newly admitted air has expanded throughout the system, the pressure within the cavity 183 is still below the pressure of the sea, the above operations repeat themselves.

When the pressure of the sea becomes less than the pressure of the air in the cavity 183, the diaphragm 181 is deflected upward and the shoulder 179 on the rod 178 is brought to bear against the valve disk 174, sliding it away from its seat 172 and opening the valve. Air then exhausts from the cavity 183 through the open valve and the exhaust tube 161, reducing the pressure in the cavity 183 and in the conduit 187. The excess air is exhausted from the system preferably into the submarine itself, since if it were exhausted outside of the submarine 10, telltale bubbles would appear in the sea. When the pressure in the conduit 187 and in the upper part of the negative differential valve 192 drops suciently, the air pressure in the hovering tank 153, acting through the conduit 159, forces back the valve disk 197, allowing air to escape from the hovering tank 153.

The total force on each of the valve disks 194 and 197 of the differential valves 191 and 192 is a combination of the force exerted on each disk by each of the springs 195 and 198 and the force exerted on each disk by the pressure of the air on the top face of each disk. When the force exerted by the pressure of the air on the lower face of a disk exceeds the total force exerted on the top' face of the disk, the disk is unseated to open the valve. The compression of the springs and 198 should be adjusted so that the force exerted by each of them upon the top faces of their respective valve disks is equivalent to the force exerted by the air on the lower face of the disks when the air is at a pressure which is greater than the pressure of the air on the other face of the disk by the maximum allowable pressure difference between the sea and the hovering tank 153.

The hovering tank is closed with respect to the submarine 10 because the tank 153 is preferably maintained at a pressure which is near pressure ambient the submarine 10 to limit the amount of Work performed by the pump 152. The inside of the submarine 10, on the other hand, is preferably maintained at approximately atmospheric pressure for the comfort of the crew. When this consideration is not applicable, and for shallow submergence, the hovering tank 153 may be open to the interior of the submarine 10. The differential pressure valves 163 could then be eliminated or modied.

The mere introduction into or removal from the hovering tank 153 of the sea water, does not, in itself, change the4 buoyancy of the submarine 10. It is the `substitution of the sea water for the lighter air and the subsequent change in the volume of the air within the tank 153 which changes the buoyancy of the submarine 10.

Obviously many modications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

l. ln apparatus for maintaining a buoyant object oating in a liquid at a substantially constant distance below the surface thereof, the combination of a direct current generator having a first and a second eld winding; first and second rectifier means; a irst magnetic amplier means having a first control winding and a first impedance winding; a second magnetic amplifier means having a second control winding and a second impedance winding; means for connecting said first eld winding, said first rectifier means, and said first impedance winding to a source of alternating current; means for connecting said second field winding, said second rectifier means, and said second impedance winding to said source of alternating current; the direction of said current flow in said second eld winding being such that it produces a polarity therein which is opposite to that produced by said current liow in said rst field winding; rectifier means for producing a direct current iiow in said first control winding in response to a decrease in the pressure of the liquid ambient on said object below a predetermined reference pressure; other rectier means for producing a direct current flow in said second control winding in response to an increase in the pressure of the liquid ambient on said object above said predetermined reference pressure; a direct current motor energized by said generator; said direct current motor being of the type which reverses its direction of rotation when the current supplied to it by said generator reverses its direction of ow; and a pump driven by said motor, said pump being of the type which reverses the flow of the liquid pumped by it when the direction in which said pump is driven is reversed, said pump being connected to pump some of said liquid into and out of said object.

2. In apparatus for maintaining a buoyant object floating in a liquid at a substantially constant distance below the surface thereof, the combination of a diaphragm on said apparatus and movable with respect thereto, means for subjecting one side of said diaphragm to predetermined reference pressure, means for subjecting the other side of said diaphragm to the pressure of the liquid ambient o n said object, said diaphragm being moved in one direction when the pressure of said liquid ambient on said object is greater than said predetermined reference pressure and moved in a second direction when the pressure of said liquid is less than said predetermined reference pressure, a direct current generator having a first and a second lieid winding, rectifier means responsive to the movement of said diaphragm in said rst direction to energize said rst iield winding, other rectier means responsive to the movement of said diaphragm in said second direction to energize said second eld winding to have a polarity opposite to the polarity of the first eld winding when energized, a direct current motor energized by said generator, said direct current motor being of the type which reverses its direction of rotation when the current supplied to it by said generator reverses its direction of flow, and a pump driven by said motor, said pump being of the type which reverses the flow of liquid pumped by it when the direction in which said pump is driven is reversed, said pump being connected to pump some of said liquid into and out of said object.

3. Apparatus for maintaining a buoyant body at a substantially xed depth within a body of water which comprises a constant volume pressure tank secured to the buoyant body, a conduit providing communication between said pressure tank and said body of water, reversible pumping means in said conduit, a pressure sensing unit adapted to produce electrical impulses upon position variations of said buoyant body from the fixed depth, a motor generator unit operative in accordance with said impulses to actuate said pumping means and vary the water volume in said pressure tank, a compressed air source, a pressure regulator in communication therewith, said regulator having a diaphragmed compartment providing a liquid chamber in communication with the body of water and an air chamber, conduit means in communication between said air chamber and said tank, valve means in said conduit means adapted to admit air to said tank when the air pressure on the diaphragm is greater than the water pressure thereon.

4. Apparatus for hovering a submarine at a substantially iixed depth within a body of water which comprises a constant volume pressure tank secured to the submarine, a conduit in communication between said pressure tank and said body of water, a reversible pump in said conduit, a pressure sensing unit adapted to produce electrical impulses upon position variations of said submarine from the fixed depth, means to amplify said impulses, a motor generator unit operative in accordance with said amplified impulses `to actuate said pump and vary the water volume in said pressure tank, a compressed air source, a pressure regulator in communication therewith, said regulator having a diaphragmed compartment providing a liquid chamber in communication with the body of water and an air chamber, conduit means in communication between said air chamber and said tank, valve means in said conduit means adapted to admit air `to said tank when the air pressure on the diaphragm is greater than the water pressure thereon.

References Cited in the tile of this patent UNITED STATES PATENTS 1,373,329 Hoar Mar. 29, 1921 1,481,230 Rovetto Jan. 15, 1924 2,130,929 Rocard Sept. 20, 1938 2,263,553 Borracci Nov. 25, 1941 2,302,014 Fausek et al. Nov. 17, 1942 FOREIGN PATENTS 322,471 Germany June 30, 1920 

